Enantioselective process for producing 1-betamethylcarbapenem antibiotic intermediates

Abstract

A process is described for the stereochemically controlled synthesis of intermediates useful in producing 1-betamethylcarbapenem antibiotics.

What is claimed is: 
     
       1. A compound of the formula: ##STR90## wherein X 1  and X 2  are independently O or S, R 1  is C 1  -C 4  lower alkyl or alkoxyl, R 4 , R 5  and R 6  are independently selected from H, C 1  -C 4  alkyl, C 7  -C 10  aralkyl, C 6  -C 10  aryl, C 7  -C 10  alkaryl, which can be substituted with --OH, --OR 10 , --SH, SR 10 , where R 10  is C 1  -C 4  alkyl, with the proviso that R 4  and R 5  are not identical. 
     
     
       2. The compound of claim 1 wherein R 4  is sterically larger than R 5 . 
     
     
       3. The compound of claim 2 wherein R 1  is beta-methyl. 
     
     
       4. The compound of claim 2 wherein R 4  and R 6  are independently selected from C 1  -C 4  linear or branched alkyl, C 7  -C 10  aralkyl or C 4  -C 10  aryl. 
     
     
       5. The compound of claim 1 wherein X 1  and X 2  are oxygen. 
     
     
       6. The compound of claim 1 of the formula: ##STR91## wherein R 4  is isopropyl or phenyl and R 6  is respectively, hydrogen or methyl.